Accelerator- and laser-based sources of high-field terahertz pulses

Abstract

At present we are witnessing a rapid development of sources for terahertz (THz) pulses with very strong electromagnetic fields. These pulses are reaching a stage where they can be used to not only probe, but also uniquely control a variety of processes that range from fundamental dynamics in individual atoms and molecules, through phase transitions in solids to a wealth of interactions in biological materials. In this review, we are presenting an overview of two major directions in the generation of such radiation. Large-scale accelerator-based sources offer unprecedented pulse energies coupled with a wide tuning range and extreme repetition rates. Laser-based sources, on the other hand, are laboratory-scale instruments and thus are very attractive in their availability to the wide scientific community. The capabilities of different variants of these THz sources are evaluated and compared with each other. In addition, powerful techniques for the temporal characterization of THz pulses are discussed.

THz pulse doubler at FLASH: double pulses for pump–probe experiments at X-ray FELs

“…The X-ray free-electron laser FLASH1 at DESY in Hamburg, Germany, has a worldwide unique feature -a THz undulator behind the main X-ray undulator section, that allows users to perform pump-probe experiments with ultrashort highintensity THz and soft X-ray pulses (Gensch et al, 2008;Frü hling et al, 2009;Tavella et al, 2011;Stojanovic & Drescher, 2013;Oelze et al, 2017). The wavelength range can be tuned from 1 to 300 mm (1 to 300 THz), depending on the electron beam energy.…”

Tailoring of Highly Intense THz Radiation Through High Brightness Electron Beams Longitudinal Manipulation

“…THz-based technologies and research applications have seen a rapid increment in the last years due to the development of new radiation sources based both on femtosecond lasers and sub-picosecond electron bunches [1,2].…”

“…Recently, laser-based sources have reached pulse energies on the level of tens of µJ by optical rectification of mJ laser pulses [2,5,6]. However, photon down-conversion process suffers of limitations to generate high power THz pulses, like the damage threshold of the nonlinear crystals and saturation conversion efficiency.…”

Monocolor Radiation Source Based on Low-Energy Electron Beam and Dc Fields With High Gradient of Electromagnetic Energy Density

“…Pursuing a high total power often drive people to consider a technique route based on electron beam [1][2][3][4][5][6][7][8][9][10][11][12]. Many routes of radiation generation [1][2][3][4][5][6][7][8][9][10][11][12] hire the electron beam in different ways. For example, in free electron laser (FEL) [1,2], an electron beam interacts with a combined field of magnetic components and incident electromagnetic (EM) wave to generate radiations at new frequency components differing from the incident wave.…”

“…Many routes of radiation generation [1][2][3][4][5][6][7][8][9][10][11][12] hire the electron beam in different ways. For example, in free electron laser (FEL) [1,2], an electron beam interacts with a combined field of magnetic components and incident electromagnetic (EM) wave to generate radiations at new frequency components differing from the incident wave. Bremsstrahlung refers to the interaction of such a beam with 3-D ionic Coulomb potential and usually has a broad frequency spectrum [13].…”